Biological Science 101 – General Biology
Lecture Four: DNA Technology
Ch. 14, Pgs. 262-267
Ch. 20, Pgs. 396-407, 412-423
Mendelian Inheritance of Traits
Inheritance of Traits:
- Genes are passed on from one generation to the next.
- Humans have 21,000 genes.
- Rice Plant has 40,000 genes.
- Mice have 22,000 genes.
Chromosomes and Gene Mapping
Chromosomes contain genes.
- 23 sets of chromosomes = 46 (Humans).
- Carrots have 14 chromosomes.
- Cucumbers have 12 chromosomes.
- Sequence the entire genuine (identify genes).
- Humans have 3 billion bases.
- Identifies genes related to diseases.
Gregor Mendel (1822-1884)
- Gardening of peas.
- Made crossbreeds.
- Studied various traits (phenotypes).
Dominant – Purple flower phenotype. (AA)
Recessive – White flower phenotype. (aa)
- Traits transmitted.
- Traits independently transmitted. Recessive genes in Humans:
- Sickle cell anemia.
- Cystic fibrosis (defective transport protein) -> involved in the transmission of
“Genetics”: The study of genes in populations and generation.
Environment is very important for gene expression.
- Identical twin studies.
Recombinant DNA Technology
1) DNA Fingerprinting
- Identifying specific individuals based on their DNA sequence.
- Every person has a unique DNA pattern.
- Used to solving murder cases, crime cases, paternity cases.
Steps to DNA Fingerprinting:
a) Extract DNA, cut with restriction enzymes.
b) DNA bank established.
c) Recognizes a specific sequence and cuts the DNA.
- Separate DNA pieces based on size.
RFLP = Restriction Fragment Length Polymorphism 2) Polymerase Chain Reaction (PCR)
- To amplify DNA from very small samples.
- Need primers, nucleotides and DNA polymerase.
E.g. Used in forensic science.
3) Gene Cloning and Recombinant DNA
a) Isolate gene of interest.
b) Transfer gene to another organism.
- Express a unique protein in an organism (E.g.
Insulin, Growth hormones)
- Organism easiest to use is Bacteria.
- Insert and express a new
(foreign) gene, Genetic Engineering:
- Insert and express a new (foreign) gene,
Bacterial genes -> plants
Fish gene -> plants Genetically Modified Foods (GMO’s)
Human gene -> bacteria